Depilatories have been used for quite a period of time to remove body hair. Depilatory for such use usually requires application times of at least 15 minutes, and often up to 20 or 30 minutes, for adequate depilation. Along with adequte hair removal, the composition must exhibit little if any skin irritation.
Depilatory compositions are generally available in the form of powders, creams, and aerosol foams.
A use for depilatories also exists in the removal of facial hair, especially for Negro males. The facial hairs of such individuals tend to ingrow quite easily with the result of a benign non-contagious dermatitis of the beard area clinically known as Pseudo-Folliculitis Barbe. This is caused by the removal of facial hair with the aid of a razor which generally leaves relatively sharp points on the ends of the hair, with the resulting pointed hair readily penetrating the face, if the hair has sufficient curl to cause the point to contact the skin prior to the next cycle of hair removal, such as shaving. Thus, a substantial need exists among Negro males for a facial hair depilatory. Several facial hair (beard) depliatory products have been previously marketed, but most of these products have been marketed in the form of dry powders, which must be mixed with water just prior to application to the face. No fast cutting facial hair (beard) depliatory creams have been marketed to date, because of the instability of some of the advantageous depilatory components in cream form, and/or irritability.
When the facial hair of Negro males is removed by a chemical agent or depilatory, the hair end is generally soft and fluffy, and generally will not penetrate the skin if allowed to contact the skin surface. Thus, a significantly reduced incidence of ingrown facial hairs can be observed by using chemical depilatory agents. Normally, however, because of the fact that the depilatories must be strong enough to remove facial hair within a short period of time, e.g. 4 - 7 minutes or so, the depilatories exhibit some irritation to the skin. Because of this skin irritation, it is generally recommended that chemical depilatories be used not more often than every other day, with no hair removal on the alternate days.
The use of alkali metal and alkali earth metal salts of .alpha.-and .beta.-mercapto carboxylic acids as depilatory agents is known to the art, note, e.g., U.S. Pat. No. 2,823,168 and 3,154,470.